2011 Payne-Gaposchkin Medal and Prize

For the development of Helioseismology into a unique quantitative tool probing the deep interior of the Sun, illuminating stellar structure and evolution and the solar neutrino problem.

Yvonne Elsworth created a quantitative spectroscopy to study the deep interior of the Sun from the pioneering work of the 70’s and 80’s on global solar oscillations. The global autonomous network of observatories she initiated has provided the definitive data on several substantial issues. Initially in the early nineties it revealed that the solar core was consistent with a standard solar model – providing the first indication that in the Solar Neutrino problem solar models were not in error, which led to the deduction of neutrino masses. Secondly her work showed the core of the Sun rotated more slowly than the surface, necessitating a dramatic theoretical re-evaluation and having consequences for the angular momentum evolution of stars.

An enduring theme continuing to the current day is studying the solar cycle in the deep interior and relating this to the magnetic activity on the surface. The network itself is the most successful autonomous such entity and has set the standard for others to emulate.

More recently there have been important developments in Professor Elsworth’s work. Firstly, that new solar abundances are inconsistent with the helioseismology data both in the core and convection zone. This remains an important challenge to theory, as abundances underlie all stellar models. The studies of the solar activity cycle have taken on great topical interest as there is evidence that the Sun may be heading for another long-term minimum in activity. Secondly, there has been a major extension of the work into the study of solar-like oscillations on other stars including red giants – the fate of our Sun.